South Umbarka area is located in the northern part of the northern Western Desert of Egypt, about 450 kilometers west of the Alexandria city. The Lower Cretaceous sands (Alam El Buieb "AEB" sands) are the main hydrocarbon reservoirs. They are found to be stratigraphically variable from well to another. The thicknesses of the sands, their shale content and porosity were found to be obviously variable. Studying the impacts of these variations on the seismic signatures of these sands would help in understanding their environment and distribution.
1-D and 2-D modeling packages were used to synthesize the effects of variations of each parameters. The modeling shows that many of these sands thickness are much thinner than seismic resolution limits (< 150 feet) and they are combined together and imaged as package. The shale-out/sand-out model demonstrates how lithology can disguise the interface between AEB-C shale-AEB-D1 sand to the point that it will be inaccurately picked. The porosity model indicates that porosity can have a large effect on the seismic amplitude.
2-D modeling shows that the interface between AEB-C shale-AE-D1 sand changes its amplitude and phase while the AEB-D1 sand consists of overlapping sand lenses separated by thin ribbons of shale.